TISat-1 is a student-developed low-cost CubeSat mission of SUPSI (Scuola Universitaria Professionale della Svizzera Italiana — University of Applied Sciences of Southern Switzerland), Lugano-Manno, Switzerland. The satellite was named after the home state (Kanton Ticino - abbreviated as TI) where Lugano is located.

The project started in 2005. The mission goals are to carry out material degradation tests on conductors of different materials and to validate the multitechnology, fault-tolerant design scheme of the spacecraft bus. COTS (Commercial-off-the-Shelf) componets are used for the whole design except for the photovoltaic cells. 1)2)3)4)5)

Figure 1: Illustration of the TISat-1 CubeSat (image credit: SUPSI)

Spacecraft:

The spacecraft complies to the CubeSat standards in size (10 cm side length) and mass (? 1 kg). The aluminum mechanical structure of TISat-1 has been manufactured by RUAG Aerospace in Lodrino (TI, CH). The overall design, validation and refinement was made at SUPSI.

Figure 2: View of the TISat-1 bus structure (image credit: SUPSI)

The attitude is passively controlled with a permanent magnets orienting the spacecraft along the Earth's magnetic field lines (magnetic bars are integrated in the mechanical structure). Some damping is provided by the magnetic hysteresis of the internal gear.

The three processor approach for the C&DHS represent a technology validation. The objective is to test fault tolerance and system availability. The modulation schemes implemented for TIsat-1 are in firmware except for the command channel which features a DTMF (Dual-Tone Multi-Frequency) transceiver chip. The housekeeping strategy are based on decision tree methodologies. These concepts are to be validated for use in future SUPSI-SpaceLab missions.

Figure 3: Layout of the C&DHS (image credit: SUPSI)

EPS (Electric Power Subsystem): All sides of the satellite are equipped with photovoltaic modules so that during any orbital day period energy generation is provided at any attitude. The modules feature six single junction 20 mm x 40 mm GaAs solar cells (19.5% efficiency, AM0). Encapsulation and wiring (chip & wire technology) of the modules has been provided by Metallux S.A. in Mendrisio (TI, CH). Two batteries are being used: a Lithium-Ion battery (2300 mAh) and a Lithium-Polymer battery (1500 mAh).

RF communications: Use of amateur radio VHF/UHF (144/430 MHz) bands. A CW (Continuous Wave) beacon is at 430 MHz. SUPSI maintains local and remote (mountain side) ground stations for communications with the spacecraft. In addition, Ham radio support is expected from the amateur community.

The antenna hold and the deployable parts are original designs of SUPSI-SpaceLab and were manufactured, tested and optimized at SUPSI-SpaceLab. The delpoyed monopole antennas are mounted 90o to the attitude alignment axis and to each other.

Launch: TISat-1 was launched on July 12, 2010 as a secondary payload on the PSLV vehicle of ISRO (PSLV-C15). The launch site was SDSC (Satish Dhawan Space Center) SHAR, the ISRO launch center on the south-east coast of India, Sriharikota. 6)

The primary spacecraft on this flight was CartoSat-2B of India (694 kg), funded by the Ministry of Defense of the Government of India. 7)

• AISSat-1 (Automatic Identification System Satellite-1), a nanosatellite (6.5 kg) of Norway with program management by the FFI (Norwegian Defense Research Establishment). AISSat-1 was built by UTIAS/SFL (University of Toronto, Institute for Aerospacestudies/Space Flight Laboratory), Toronto, Canada.

AISSat-1 and TISat-1 were deployed into space using the XPOD (Experimental Push Out Deployer) provided by UTIAS/SFL. UTIAS/SFL refers to this service as NLS-6 (Nanosatellite Launch Service-6). 8)

• StudSat (Student Satellite), a picosatellite (1 kg) built by a consortium of seven Engineering colleges from Hyderabad and Bangalore, India.

• April 14, 2015: In its 5th year on orbit, the TISat-1 CubeSat mission is still being received by ham operator ground stations worldwide. Data is being collected in order to assess system endurance/degradation. The negotiated radio link frequencies are still reserved for TISat-1. The original mission goals have been reached and surpassed by far. In this sense the mission is concluded (Ref. 9).

• March 2014: TISat-1 is still operational. The project continues to monitor the CubeSat. Signal quality and system health information is being collected (Ref. 9).

• March 2013: TISat-1 is operating nominally. The project continues to monitor its on board material probes (Ref. 9).

• In 2012, TISat-1 is still in good shape and working. The CubeSat is being monitored now mainly by amateur radio operators who make a great job in recording and submitting telemetry data to SUPSI-SpaceLab (Ref. 9).

• In the early days of 2011 two-way FM radio communication was established with TIsat-1. Commands are being sent and responses are collected, as expected.

Data is being collected with the help of the Ham radio community. In addition to our local experiments, Japanese hams and radio amateurs from New Zealand and Brazil are providing regular feedback.

Sensor complement: (AOE)

AOE (Atomic Oxygen Experiment):

The objective is to monitor the durability of exposed thin bonding wires, PCB tracks and lines. Atomic oxygen is a molecular constituent of oxygen in the atmosphere and is very aggressive on many materials. Satellites orbiting in LEO (Low Earth Orbit) are exposed to atomic oxygen attacks.

TISat-1 carries the AOE apparatus to verify the durability of conducting wires (different materials, different cross sections) and nylon lines exposed to the space environment. The bonding wires on the six external sides of TISat-1 will constantly be monitored. It is expected that if a wire is attacked, it will break open. TISat-1 will be able to tell how long those wires survive in LEO conditions.

The information compiled and edited in this article was provided byHerbert J. Kramer from his documentation of: "Observation of the Earth and Its Environment: Survey of Missions and Sensors" (Springer Verlag) as well as many other sources after the publication of the 4th edition in 2002. - Comments and corrections to this article are always welcome for further updates (herb.kramer@gmx.net).